A preparation to be used as an ink for ink jet printing is for instance known from the document EP 1690903 A. Therein, it is an aqueous ink for use on a sucking substrate, as for instance letter envelopes. If an organic polymer is provided, it does not serve as a binding agent, but as an additive for viscosity adjustment. Such inks cannot be used for printing on polycarbonate films for the following reasons explained with regard to paper-based security and/or value documents.
A personalization of PC (polycarbonate) based security and/or value documents takes place in the practice by means of the so-called laser engraving method, wherein by optical/thermal interactions of a material of the security and/or value document with the laser radiation, locally highly resolved pyrolysis processes are produced and thus local blackenings due to carbon generation occur. The disadvantage of this method is the limitation to black & white or at best gray scale representations.
A colored personalization established for paper-based documents in the ink jet printing method is not widely used for PC based security and/or value documents up to now. One reason for this is the lacking compatibility of the used polymers/binders (in connection with the other ink components such as dyes, additives, solvents) with polycarbonate. This applies for instance to the binders known from the documents Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release 2007, Wiley Verlag, chapter “Imaging Technology, Ink-Jet Inks, and Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release 2007, Wiley Verlag, chapter “Paints and Coatings”, such as nitrocellulose, cellulose ester (cellulose acetate butyrate, CAB), polyacrylates, polyesters, epoxides etc. Secondly, PC films imprinted with such inks cannot easily be laminated. PC films imprinted over the full surface practically cannot be laminated at all, for the dye layer represents a barrier layer. In the event of an only partial printing process, there is the risk of a local delamination. Thirdly, polycarbonate is no sucking base. Common inks for ink jet printing are adjusted to good absorption times on paper and when imprinted on a non-sucking PC film they remain on the surface and can even after drying often completely be removed without residues, since the color does not penetrate into the material. Fourthly, ink jet printing layers made from insofar known inks lack temperature stability. Since in the field of security and/or value documents, imprinted PC films are typically laminated to each other under the action of pressure (>2 bars) and temperature (>160° C.), there is a risk of discoloration of the ink jet printing layer.
From the document EP 0 688 839 B1, silk-screen printing inks based on disubstituted dihydroxydiphenyl cycloalkanes are known. From this document can also be taken methods for making such polycarbonates. This document with its complete contents is hereby included in the scope of disclosure of the present application. Normally silk-screen printing inks can however not easily be used for ink jet printing, since ink jet printing poses special requirements for the used inks because of the nozzle technology of the printing heads.